The present invention relates to a vehicular electronic key system for unlocking/locking vehicular doors and starting an engine. The electronic key system includes an electronic key and an on-vehicle apparatus which is communicable with the electronic key by means of wireless communication, and identifies ID (identification data) between the electronic key and the on-vehicle apparatus to permit the door unlocking/locking operation and the engine starting operation.
A Japanese Utility Model Provisional Registered No. 2511202 discloses a vehicular electronic key system arranged to warn a driver that an electronic key has been mislaid in a passenger compartment when the driver opened a driver door.
However, such a vehicular electronic key system requires a large magnetic field generator or a plurality of small magnetic field generators, which can form a magnetic field in a vehicle passenger compartment, so that the system can detect an electronic key mislaid in a passenger compartment. This provision of such a large magnet field generator or plurality of small magnetic field generators increases energy consumption of a vehicle.
It is therefore an object of the present invention to provide an electronic key system which is capable of preventing a driver from mislaying an electronic key in a passenger compartment by employing a necessary minimum numbers of small antennas.
An electronic key system according to the present invention is for a vehicle and comprises a portable apparatus and an on-vehicle apparatus. The portable apparatus comprises a first wireless communication device and a first memory storing a key ID (Identification Data). The on-vehicle apparatus is installed in the vehicle and comprises a second wireless communication device, a second memory storing an apparatus ID, a door condition detector, and a control unit. The second wireless communication device is communicable with the first wireless communicating device when the first wireless communication device is located in a predetermined area outside of the vehicle. The door condition detector detects that a locking operation of the vehicle door is executed from the outside of the vehicle. The control unit locks the vehicle door when the key ID corresponds with the apparatus ID. The control unit outputs alarm when the locking operation of the vehicle door is executed from the outside of the vehicle and when the second wireless communication device is not capable of communicating with the first wireless communicating device.